Effects of lithology and geomorphology on sediment yield in karst mountainous catchments

Abstract

Due to the characteristics of the lithology and the complexity of the geomorphology, the karst areas of Southwest China are experiencing severe soil erosion. Knowledge of the effects of lithology and geomorphology on sediment yield are therefore essential for developing measures to effectively control sediment delivery in this region. The objective of this study was to investigate the relative importance of lithological and geomorphological factors for sediment yield in 40 selected karst mountainous catchments in Southwest China. Because of the high co-dependence of these variables, a partial least squares regression (PLSR) model was used to explore the quantitative relationships between annual sediment yield and 30 lithological and geomorphological factors. Results showed that the lithology and geomorphology were critically important to annual sediment yield and could explain 65.9% of the total variance in sediment yield. The dominant lithological and geomorphological factors controlling annual sediment yield were karst coverage, drainage density, basin relief, plane curvature, elevation, maximum elevation, average slope, dolomite coverage, relative relief, and catchment area. This importance or these contributions of lithological and geomorphological factors to annual sediment yield provides a good reference for selecting key factors when developing soil erosion models. This study yields a greater understanding of the influences of lithology and geomorphology on sediment yield, and is helpful for better catchment management in karst regions.